“That would be Congress. They vote appropriations.”
Last time I checked, no appropriations bill can become law without the president’s signature. Yes, Congress is jointly liable for the mess, but that doesn’t preclude suing POTUS for his responsibility.
I obviously don’t believe one could actually sue Obama for these damages (though it would be interesting to see what happened if someone tried to drag him into small claims court for recovery). My larger point is that Obama’s policy have wreaked untold damage to the U.S. and its citizens left holding the bag—to the tune of thousands of dollars. It’s astonishing those citizens don’t have standing to sue over whether he legitimately holds his office.
Last time I checked no bill reaches the President without Congress first approving it. Even if this was an actionable offense, you'd have a hard time hanging it on Obama alone. So keep on trying.